A strut-type suspension used for a front wheel of a four-wheeled vehicle generally includes a strut assembly combined with a coil spring. The strut assembly has an external cylinder that is integrated with a main shaft and in which a hydraulic/gas shock absorber is incorporated.
Strut-type suspensions can be classified based on whether a piston rod of the strut assembly rotates or not when the strut assembly rotates with the coil spring under steering operation. In either case, a thrust bearing is used between an attachment mechanism of the strut assembly for attaching to the vehicle and an upper end portion of the coil spring for allowing smooth rotation of the strut assembly.
Conventionally, there is a suspension control apparatus that includes, as a strut bearing for a vehicle, a top cup into which an upper end portion of a piston rod used in a shock absorber of a strut-type suspension is inserted, a bottom cup on which the top cup is provided so that the bottom cup is rotatable with respect to the top cup about an axial center of the piston rod, a rotating member that is provided in an annular space formed between a fixed top race connected to the top cup and a rotating bottom race connected to the bottom cup for receiving a thrust load of the piston rod, a coder that is rotatably attached to the rotating bottom race and generates a pulse, and a sensor that is fixed to the coder and detects a pulse for measuring a rotating angle of the rotating bottom race (See Patent Literature 1).
Also, there is another suspension control apparatus that includes, as a strut bearing for a vehicle, a top cup into which an upper end portion of a piston rod used in a shock absorber of a strut-type suspension is inserted, a bottom cup on which the top cup is provided so that the bottom cup is rotatable with respect to the top cup about an axial center of the piston rod, a rotating member that is provided in an annular space formed between a fixed top race connected to the top cup and a rotating bottom race connected to the bottom cup for receiving a thrust load of the piston rod, and a deformation sensor that is connected to the top cup and the bottom cup, which are fixed members, and measures the amount of deformation of the fixed members due to a force acting on a wheel (See Patent Literature 2).